Impeller making



NOV. 28, 1967 D. w. JAMES 3,354,529

IMPELLER MAKING Original Filed July 29, 1965 DAV/D W. JAMES INVENTOR.

BY f W I United States Patent Ofi 3,354,529 Patented Nov. 28, 1967 ice3,354,529 IMPELLER MAKING David W. James, Allen Park, Mich, assignor toFord Motor Company, Dearborn, Micl1., a corporation of Delaware Originalapplication July 29, 1963, Ser. No. 298,158, now Patent No. 3,246,607.Divided and this application Oct. 19, 1964, Ser. No. 404,841

3 Claims. (Cl. 29156.8)

This application is a division of copending application S.'N. 298,158,filed July 29, 1963, now Patent No. 3,246,- 607, in the name of David W.James, and assigned to the assignee of this application.

This invention relates to an impeller and to the method of making animpeller. More specifically, the invention relates to a plastic pumpimpeller and to the method of making a plastic pump impeller in which aceramic sealing member and a metal hub are molded into the plasticmaterial.

In present day passenger automotive vehicles the water pump impeller isconstructed of cast iron. It is housed in a cast iron housing thatrotatably supports the impeller shaft by means of a bearing. A sealingmember carried by the housing and engaging the cast iron impellerprovides a seal that is designed to exclude from the bearing Water orthe fluid that is being pumped. If Water does reach this hearing itinvariably reacts with the lubricant employed to lubricate the bearingand causes a bearing failure.

Considerable difliculty has been experienced with the pump constructiondescribed above. The sealing member carried by the housing has worn agroove in the cast iron and this has caused leakage of the seal. Thebearings that journal the impeller shaft have in turn failed.

The present invention has been developed to solve this problem forpassenger automotive vehicles where low cost and simplicity areessential. It comprises a plastic impeller body molded about acylindrical metal hub and a ceramic sealing member. The cylindricalmetal hub is adapted to receive the impeller driving shaft and theceramic sealing member has an annular face adapted to engage a sealingmember carried by the pump housing. The ceramic sealing member,preferably composed of aluminum oxide, is sufficiently hard that thesealing member carried by the pump housing will not wear it appreciably.This gives a long life seal and substantially eliminates bearingfailures.

The pump impeller is made by placing the ceramic sealing member,preferably in the form of an annulus, in a mold. The metal hub has anannular frangible edge that is positioned against the ceramic sealingmember. An axial force is applied to crush the frangible edge intosealing engagement with the ceramic sealing member. Plastic moldingcompound is injected into the mold around the circumference of the metalhub and ceramic sealing member to form the main body portion of theimpeller. The molding compound molds the ceramic sealing member and themetal hub in place, and the crushed frangible edge of the metal hubmember forms a seal between the metal hub and the ceramic sealing memberso that the plastic molding compound that is injected around theperiphery thereof does not enter the internal diameter of the hub andthe sealing member.

The ceramic sealing member is preferably positioned coaxially withrespect to the metal hub and has an internal diameter slightly greaterthan this metal hub. The

molding operation leaves an exposed annular face positionedperpendicularly with respect to the axis of the metal hub and the shaftthat is received by the metal hub. This annular face provides thesealing surface that engages the sealing member carried by the pumphousing.

An object of the invention is the method of making a molded plastic pumpimpeller that has a ceramic sealing element and a metal hub molded intothe main body portion of the impeller.

Other objects and attendant advantages of the invention will become moreapparent as the specification is considered in connection with theattached drawings, in which:

FIGURE 1 is a partial sectional view of a pump assembly including theimpeller of the present invention;

FIGURE 2 is a partial sectional view of the ceramic insert and the metalhub placed in contact with one another prior to manufacturing operationsand showing a portion of the body of the impeller in phantom form;

FIGURE 3 is a view similar to FIGURE 2 showing the completed pumpimpeller;

FIGURE 4 is a view similar to FIGURE 3 of an alternate construction ofthe invention, and

FIGURE 5 is a plan view of one form of the ceramic sealing member orinsert used with the embodiment of the invention shown in FIGURE 4.

Referring now to the drawings in which like reference numerals designatelike parts throughout the several views thereof, there is shown inFIGURE 1 a pump assembly 10 that includes a pump impeller 11 having amain body portion 12 of molded plastic. This main body portion 12carries a metal hub 13 and a ceramic sealing member or insert 14positioned in contact with the hub. The ceramic sealing member or insert14 has an annular face or sealing surface 15 that cooperates with anannular sealing member 16 carried by the housing 17 of the pumpassembly.

The annular sealing member 16 is supported in the housing 17 by means ofa structure that includes a metal cup member 18 that is positionedwithin a counter bore 21 in the housing. This metal cup member may besealed in the counter bore 21 by means of any suitable sealing compound.A flexible elastomeric sleeve 22 is carried by the metal cup member 18and it has an annular flange 23 that engages the bottom of the metal cupmember 18 and a second annular flange 24 that engages the sealing member16. A helical spring 25 is positioned in engagement with the two annularflanges 23 and 24 of the elastomeric sleeve 22. This helical springserves the purpose of spring loading the annular sealing member 16 intoengagement with the annular face 15 of the ceramic sealing member orinsert 14.

A shaft 26 is rotatably journaled in the housing 17 by means of bearings27 and 28 that may be of the permanently lubricated type. The shaft 26extends through the housing 17, through the metal cup member 18 of thehousing, through the annular sealing member 16, through the ceramicsealing member or insert 14, and is secured to the metal hub 13 of thepump impeller 12 by any suitable means, for example, by press fitting.The shaft 26 has suflicient clearance with respect to the metal cupmember 18 and the annular sealing member 15 so that it can rotate freelywith respect to these elements.

As can be seen by reference to FIGURE 1, the impeller carries aplurality of blades 31 and 32, and the pumping area of the pump assembly10 is in the immediate vicinity of these bladeshThe purpose of theceramic sealing member or insert 14 with its annular face 15 and thesealing member 16 is to provide an annular running seal that willprevent the fluid being pumped, for example, an internal combustionengine coolant, from entering the area of the bearings 27 and 28. Aspreviously pointed out, if the fiuid being pumped does reach thebearings 27 and 28, failure of these hearings will occur. It should benoted that the annular face 15 of the ceramic sealing member or insert14 and the complementary face on the annular sealing member 16 arepositioned perpendicularly with respect to the axes of the metal hub 13,the ceramic sealing member or insert 14 and the shaft 26.

The ceramic insert 14 can be conveniently made of aluminum oxide that isapproximately 85% pure. The remaining ingredients, such as silicon andother impurities, permit binding of the aluminum oxide into a hard bodywhen passed through a sintering furnace. The metal hub 13 may beconstructed of SAE 1010 steel, while conventional phenolic moldingcompound may be used to form the main body portion 12 of the impeller11. The annular sealing member 16 may be made of a phenolic moldingcompound with impurities of carbon and soft metal for lubricatingpurposes.

Referring now to FIGURE 2, the metal hub 13 and the ceramic sealingmember or insert 14 are shown positioned together as they would be in amold prior to the molding process. It can be seen from this figure thatthe metal hub 13 has an annular frangible knife-edge 35 positioned incontact with a face 36 of the ceramic sealing member or insert 14 thatis positioned opposite the annular face or sealing surface 15. The metalhub 13 is also knurled on its outer periphery as is the ceramic sealingmember or insert 14 at various positions on its periphery indicated bythe numeral 37. The knurled portions 37 may have a slightly largerdiameter than the remainder of the ceramic insert 14 as shown in FIGURE2. The ceramic insert may also have an annular groove 38 positioned inthe face 36, the purpose of which will be described subsequently.

Prior to injecting the phenolic or plastic molding compound into themold to form the main body portion 12 of the impeller, an axial force isapplied on the metal hub 13 and the ceramic sealing member or insert 14to crush the annular frangible knife-edge 35 against the ceramic sealingmember or insert 14 to form an annular seal between these two members.The crushed frangible edge of the metal hub 13 is shown in FIGURE 3, andit provides, in cooperation with the annular face 36 of the ceramicsealing member or insert 14, a seal having a considerable radialthickness. When this operation has been completed the mold is closed andthe plastic or phenolic molding compound is injected into the moldaround the periphery of the metal hub 13 and the ceramic sealing memberor insert 14. The seal formed by the crushed frangible knife-edge 35 andthe annular face 36 prevents the phenolic or plastic molding fromentering the internal diameter of these two members. This assures aproperly molded main body portion 12 of the pump impeller 11 and alsoassures that the internal diameter of the metal hub 13 and the ceramicinsert or sealing member 14 will be free of material so that the shaft26 can freely enter these two members.

It can be seen also that the knurled edges 37 that are of greaterdiameter than the remainder of the ceramic insert 14 permit the ceramicinsert to be enveloped by the plastic or phenolic molding material andprevent axial and rotary shifting of the ceramic insert 14. The groove38 prevents transverse shifting of the ceramic insert with respect tothe axis of the metal hub 13 and the shaft 26. As can be seen byreference to FIGURE 3, the molding compound of the main body portion 12extends only about half the axial distance between the annular face 36and the annular face 15 of the ceramic sealing member or insert 14, Thislea es the annular face 15 of the ceramic insert or sealing member 14exposed so that it can engage the annular sealing member 16.

An alternate embodiment of the invention is shown in FIGURE 4 and thealternate form of the ceramic sealing member or insert 14 used with thisembodiment is shown in FIGURE 5. In this alternate embodiment thefrangible knifeedge 35 of the metal hub 13 is positioned at the outerdiameter thereof, and the ceramic insert or sealing member 14 isprovided with grooves 39 at the outer periphery thereof that prevent thetransverse shifting of the ceramic insert 14. The knurled portions 37 ofthe ceramic insert in this case may be tapered as shown at FIGURE 4 sothat the phenolic or plastic molding compound forming the main bodyportion 12 of the impeller 11 envelopes the insert and prevents it fromshifting axially.

The invention thus provides a pump impeller that has an exposed ceramicsealing surface molded into a plastic impeller body. The ceramic sealingsurface provides a durable and long life seal. This impeller isinexpensive since it uses low cost materials and no finishing operationsare required after molding. These features make it ideally suited foruse as a water pump impeller on an automotive vehicle. The inventionfurther provides a unique and eminently satisfactory method ofconstructing the impeller.

It will be understood that the invention is not to be limited to theexact construction shown and described, but that various changes andmodifications may be made without departing from the spirit and scope ofthe invention as defined in the appended claims.

I claim:

1. The method of making a molded pump impeller comprising the steps ofplacing an annular ceramic insert in a mold, placing a cylindricalmetallic hub having an annular frangible edge in the mold with theannular frangible edge in contact with said annular ceramic insert,applying an axial force to said annular, ceramic insert and saidcylindrical hub to crush said annular frangible edge into sealingcontact with said annular ceramic insert, and molding a plastic impellerbody around said cylindrical hub and said annular ceramic insert, saidannular ceramic insert and said metallic hub having means forcooperation with the molded plastic impeller body to prevent relativemotion therebetween.

2. The method of making a molded pump impeller comprising the steps ofplacing a cylindrical metal hub having a frangible end in contact withan annular ceramic insert, applying an axial force to said cylindricalmetal hub and said annular ceramic insert of sufiicient magnitude to"flatten said frangible end of said metal hub against said annularceramic insert, and molding a plastic impeller body around saidcylindrical metal hub and said ceramic insert, the flattened frangibleedge of said cylindrical metal hub in contact with said annular ceramicinsert providing a seal against the fiow of plastic into the interior ofsaid cylindrical metal hub and said annular ceramic insert, said annularceramic insert and said metallic hub having means for cooperation withthe molded plastic impeller body to prevent relative motiontherebetween.

3. The method of making a molded pump impeller comprising the steps ofplacing an annular ceramic insert in a mold, said annular ceramic inserthaving a first face and a second face, placing a cylindrical metallichub having an annular frangible edge in the mold with the annularfrangible edge in contact with the first face of said annular ceramicinsert, applying an axial force to said annular ceramic seat and saidcylindrical hub to crush said annular frangible edge into sealingcontact with said annular ceramic insert, and molding a plastic impellerbody around the periphery of said cylindrical hub and said annularceramic insert and leaving said second face of said annular ceramicinsert exposed, said annular References Cited 5 UNITED STATES PATENTS11/1933 Schopp 29-527 8/1938 Bart 29-527 6/1942 Morrell 29-527 11/1964Bruun 29 s27 10 KrOtz 264-276 Cole 264-276 Everett 264-276 Haw 264-262Blaurock 29-527 Hansz 29-527 JOHN F. CAMPBELL, Primary Examiner. P. M.COHEN, Assistant Examiner.

1. THE METHOD OF MAKING A MOLDED PIMP IMPELLER COMPRISING THE STEPS OFPLACING AN ANNULAR CERAMIC INSERT IN A MOLD, PLACING A CYLINDRICALMETALLIC HUB HAVING AN ANNULAR FRANGIBLE EDGE IN THE MOLD WITH THEANNULAR FRANGIBLE EDGE IN CONTACT WITH SAID ANNULAR CERAMIC INSERT,APPLYING AN AXIAL FORCE TO SAID ANNULAR CERAMIC INSERT AND SAIDCYLINDRICAL HUB TO CRUSH SAID ANNULAR FRANGIBLE EDGE INTO SEALINGCONTACT WITH SAID ANNULAR CERAMIC INSERT, AND MOLDING A PLASTIC IMPELLERBODY AROUND SAID CYLINDRICAL HUB AND SAID ANNULAR CERAMIC INSERT, SAIDANNULAR CERAMIC INSERT AND SAID METALLIC HUB HAVING MEANS FORCOOPERATION WITH THE MOLDED PLASTIC IMPELLER BODY FOR PREVENT RELATIVEMOTION THEREBETWEEN.